Cross country skiing involves a striding and gliding motion, which in turn requires that the heel of each ski boot be lifted and lowered relative to the corresponding ski with each kick. For this reason, the soles of cross country ski boots are typically provided with extending toe portions for connection to the ski. Cross country ski bindings are therefore adapted to allow for releasable connection to the ski boots and relative pivotal motion between the skis and ski boots.
Cross country ski bindings of the toe-binding type usually consist of a toe iron anchored to the ski and some means for releasably clamping it to the toe portion of the sole of the ski boot. The clamp often consists of resilient sturdy wire which can be moved into or out of engagement with a hook or slot to selectively clamp the toe portion of the sole of the ski boot in place. Such wire clamps can typically be manipulated with a ski pole by the skier while standing, and lugs or spikes are frequently provided on the toe iron for engaging recesses in the sole of the ski boot to constrain the ski boot against lateral, longitudinal and rotational movement relative to the ski binding. U.S. Pat. No. 3,905,612 to Kjellstrom illustrates a ski binding representative of this type.
Ski bindings of this type, however, operate primarily on a clamping principle in which the toe of the ski boot is secured directly to the ski such that the lifting action is provided by the flexibility of the boot sole. Since boot soles are not completely flexible, this tends to impair the necessary action and thus movement of the skier. In addition, such constant flexing of the boot sole tends to loosen the boots from the bindings which in turn reduces the degree of control over the skis.
The problems associated with this type of cross country ski binding have been addressed by providing toe irons with pivotal portions for connection to the ski boots in order to achieve greater freedom of pivotal movement between the boots and skis by reducing the importance of the flexibility of the ski boot soles. Ski bindings of this type have performed better than the former kind, but have tended to be relatively more complicated and thus expensive. My prior U.S Pat. No. 4,165,888 shows a ski binding having a relatively fewer number of parts and a combined clamp/hinge member to overcome some of these problems. Even this type of ski binding incorporates spikes which fit into recesses in the sole of the ski boot for additional constraint, and is thus still subject to some loosening in this regard during use.
The ski bindings of the prior art, however, have still not adequately addressed the problem of achieving positive releasable connection between the ski boots and bindings in a manner which minimizes play and improves control over the skis.